Tunable magnetron



g- 1952 M. c. PEASE ET AL 2,606,307

TUNABLE MAGNETRON Filed Jail. 29, 1946 FIG.2

FIG?) INVENTOR. MARSHALL c. PEASE FRANK A. RECORD ATTORNFY Patented Aug.5, 1952 UNITEDfSTATQES PATENT;QQFFICE V TUNABLE MAGNETRONY Mars'hall' bll'ease, Boston, Mass, and Frank A.

Recordfrot'sdamg N. Y., assignors to the United States of Americ'aasrepresented by the secre- .tary: of "War:

imi ates inner} 29, 1946, Serial No. 64 4.164;

and more particularly to'improvement's in tuneable magnetron radiofrequency oscillators.-

Various methods of tuning magnetron radio frequency oscillators; havebeendevised in the past. Many of these methods weredesigned to changethe frequency by coupling some externally tuned reactance into themagnetron resonant cavity. These designs were accompanied by a certainamount of unavoidablepower loss in the tuning reactance and in theintermediate coupling between the reactance and the magnetron cavity.

An object of the present invention is to provide a magnetron with amechanical adjustment for the resonant frequency of the magnetron cavityresonators. I I V A further object of the inventionis to' accomplishtuning of a magnetron'with negligible Other objects and advantages ofthe--invention will be apparent during the course of the followingdescription.

In the accompanying drawing forming a part of this'specification and in,which like numerals are employed to designate like parts throughout thesame,

Fig. 1 is a top view of a tuneable plural cavity magnetron embodying theprinciples of the principles or the present invention, with the'topcover removed showing the anode structure and a portion of the bodystructure broken away to illustrate the plunger rod. The bellows isshownpartially cross-sectioned; the plunger rod is not cross-sectioned. I

Fig. 2 is a side view of hejanode structure itself.

Fig. 3 is a top view of one of the fixed metallic laminations composingthe anode structure of Fig. 2.

Fig. 4 is a top view of one of the moveable metallic laminationscomposing the anode structure of Fig. 2.

Referring to Fig. 1 wherein is shown a preferred embodiment of thisinvention, the numeral I0 designates a substantially rectangularparallelepiped structure with one semi-cylindrical end which serves asthe housing for the plural cavity magnetron concentrically disposedabout central cathode I2 is the substantially cylindrical anodestructure I3. Anode structure l3 contains a plurality of individualoscillator cavities 4 leading by radial off-center slots l5 into thecathode-anode space l6 which is concentrically disposed about cathodel2.

- fiCl'aimsiiCl. 315-40) E.

Fig. 2 shows aside view oftheanode structure l3 removed from magnetronAnode structure I 3 is composed of a plurality of metallic washer-likelaminations 20, 2|, and 22 pleted anode structure l3.

Alternate metallic laminations 2|] composing I anode structure l3 arefixed laminations and the other laminations 2| and 22 are moveablecorresponding to the cavities H of Fig. 1 and radial slots l5"corresponding to the radial slots |5 of Fig. 1. 'A 'fixed-pivothole 29is provided on a boss 30 which projects from the circumference ofmoveable lamination. A second boss 3| projecting from thecircumferenceof laminations 2| has a tie hole 32 and a pivot slot Moveablel'aminations' 22 (Fig. 2) are identical with moveable laminations 2|, asshown in Fig. 4, save that the boss 3| extends only slightly beyond tiehole 32as shown by the dotted line in Fig. 4. a

Referring again to Fig. 1, a fixed-pivot pin 40 passes through thefixed-pivot hole 29 of the moveable laminations 2| and 22. A tie bolt 4|passes through the tie holes 32 of the moveable laminations 2| and 22 tomaintain their alignment. A moveable plunger rod 42 passes between theuppermost andlowermost moveable laminations 2|. A pivot pin 43 isaffixed to rod 42, said pivot pin 43 being guided in the pivot slots 33of moveable laminations 2|. Moveable plunger rod 42 has a slot 44 whichis guided by the fixed pin 45. Fixed pin 45 is aflixed to resonantfrequency of each cavity 11 and. hence i of the frequency of themagnetron II.

A tuning range of the order of is readily attainable by the use of thisdevice. lfhe inanifold variation, which alters the dimensions of eachcavity I4 and of each sIOtxiI5,-JS noteworthy as causing a large change,of -freqiiency'rorfa small rotation of the moveable"laminations 2| withrespect to the fixed laminations 20. The power output is not appreciably-afi'e(= -,v J;

While there has been described what is at it:

ment of this inventionflit will be obvious that variou changesandmodifications may be made therein withoutsdeparting:ifrom' the scope ofthe invention; J: a 1

, Whatisclaim'ed isf:

1. A 'tuneable magnetron oscillator including a substantiallycylindricahan'ode structure, an evacuated housing surroundingsaidranode:structure: said anode Structure having a central-cylindricalspace surrounded by a pluralityr of concentrically arranged cylindricalcavities about said spacez-"an'd opening into said space throughradial-slots, said anode/structure comprising va stack ofmetallic'washer'likelaminae tions, alternate laminations in saidistackbeing moveable withlrespect' to',the..others, a plunger.

rod connected with said inoveable laminations, vacuum seal meansflexibly connecting said plunger rod to said housing, andrexternaltuning drive means connected to said zplunger rod,

wherebysaid plunger rod may be moved thereby quency of said magnetronoscillator;

2. Atuneable magnetron including a 'substan-z tially cylindrical anodestructure, said anode" rtrueture' having. a, central cylindrical 1'space surrounded by, a plurality of cylindrical cavities concentricallyarranged :about said :space and opening into said space'qthrough radiali slots, anode structure comprising a stack of allic g washerelikelaminations, alternate a to h o rs-and mean -con e t o i iimoveablezlaminations; for movingsaidmoveanode structure comprising :astack of. metallic inationsin; said; stack; being; moveable, with i -.40moving said moveable jlaminations' with. respect I to said- :fixe'd jlaminations -and' varying :the' di I mensions of; saidcylindricalicirfltis and said"; radial slots andco'nsequently Evaryingthe fre-wi 4 laminations, alternate laminations in said stack beingmoveable with respect to the others and means connected to said moveablelaminations for moving them into said cavity resonators to thereby varythe resonant frequency of said cavity resonators.

In ,a tunealile magnetron,,an anode structure having a plurality'ofcavity resonators, said anode structure comprising a stack of metalliclaminations, a number of the laminations in said stack being moveablewith respect to'the others and means connected to said movablelaminations for moving them into said cavt ity resonators' o therebyvary the resonant frequency 01'- said cavity resonators.

5. A tune'able magnetron including a substan- .,tially cylindr1cal anodestructure having a central cylindrical space surrounded by a pluralitypresent considered t bemthe preferred m di; oif cylindrical cavitiesconcentrically arranged about said space and opening into said spacethrough radial. slots, said anode structure comprising a stack ofmetallic washer-like laminations,.;alternate laminations in said'stackbeing movable with respect to the others, ,,and means connected to saidmovable laminations-for rotating said movablev laminations with respectto the other laminations to I thereby .constrict each of saidcylindrical cavities and said ,radial slots.

6. A tunable magnetronoscillator having an anode structure said anodestructure comprising substantially indentically shaped washer: likelaminations, each-ofsaid laminationsbeing circular in cross-section andhaving a central circularspace surrounded by a plurality of cir cularholes concentrically arrangediabout said space and opening into saidspace through radial slots, all of said laminations being'arranged in astack with saidspaces, said-holes and said slots insubstantial,coincidence, alternate laminations in said stack being rotatably movablewith respect to theothers, and. means connected to said movablelaminations forrotating said movable laminations with respect to saidother laminations. v

l MARSHALL C.' PEASE.

-FRANK A, RECORD appearances CITED The following references areofrecord-in; the file of this patent:

UNITED STATES; PATENTS Spencer Apr. 5, 1949

